The present invention relates to a wheel suspension for vehicles, in particular commercial vehicles.
Wheel suspensions of the type mentioned above are known from U.S. Pat. No. 5,379,842. In these wheel suspensions, the floor section of the vehicle has attached to it a mounting head which carries a bracket in a manner that allows the latter to be rotated about an upright axis. The bracket is supported relative to the ground by wheels. The bracket is designed to be intrinsically vertically adjustable to ensure uniform load distribution during use on uneven terrain and when a plurality of such wheel suspensions are used as supporting units, for heavy loads for example. The mounting head carries a ring gear and the bracket, for its part, is connected, at the circumference of its top part which is supported relative to the mounting head and is not vertically adjustable, to an actuating motor which has an upright axis of rotation and engages in the ring gear by way of its drive pinion, which is provided at the upper end.
Owing to the forces acting on the wheel suspension, the central mounting for the bracket is subject to considerable loads and it is virtually impossible to keep the bracket free from play due both to assembly and to wear. A corresponding play in the mounting in conjunction with other tolerances, for example in the centering of the ring gear relative to the bearing axis, in the gearing and in the fixing of the actuating motor relative to the bracket, means that it is virtually impossible to make the pinion/ring gear pair backlash-free in operation, and play-free steering can be achieved and maintained only with difficulty.
JP-A-60 135323 has furthermore disclosed a pivoted-wheel arrangement for a truck. In the arrangement, there is a guide ring which is fixed relative to the vehicle, on the floor, determines the pivoting axis of the vehicle and is coaxial with the axis, and to which is assigned, in a coaxially torsionally rigid manner, an internally toothed ring gear and a supporting ring. The supporting ring is offset axially towards the wheel in relation to the ring gear, is rotatable, and carries the wheel with an axis of rotation perpendicular to the upright pivoting axis, an associated wheel hub motor and an upright actuating motor. The drive pinion of the latter meshes with the ring gear, allowing the rotational position of the wheel to be adjusted by the actuating motor. A design of this kind allows a relatively large diameter for the support of the supporting ring relative to the guide ring and hence comparatively low specific loads. Even with a design of this kind, however, unavoidable tolerances, load-related compliance and wear make permanently backlash-free meshing virtually impossible, with the result that play-free steering can be achieved and maintained only with difficulty.
The invention is intended to develop a wheel suspension of the type stated at the outset in such a way that, without complicating its structure, a largely play-free driving connection can be achieved between the actuating motor and the ring gear as a prerequisite for a steering system that is, as far as possible, without play.
This is achieved by a basic approach from which the invention starts, which is to use the ring gear with which the pinion of the actuating motor is to be kept in engagement as a fixed support for the actuating motor, i.e. to provide, between the ring gear and the pinion, a support which allows a largely play-free connection between the pinion and the ring gear, irrespective of any other component tolerances and instances of play due to wear and loads, in conjunction with elastic support of the actuating motor relative to the bracket.
With a view to providing as compact a construction as possible, it has proven expedient for the supporting ring to be internally toothed and for the actuating motor to receive counter support against the outer circumference of the supporting ring.
The structural complexity can be kept relatively low while ensuring a small overall volume if the actuating motor is arranged vertically on the bracket, carries the drive pinion in the upper end region and is connected to the bracket by struts that are at an angle to one another and, with the bracket as the base, form a supporting triangle in plan view. Such a solution makes it possible to keep the ring gear and the pinion in mesh virtually without play even if the actuating motor is connected to the bracket and the bracket, for its part, undergoes certain deviations from the position in which it is concentric with the supporting ring due to play and/or loads.